Overground suspension walkers elicit more and higher quality stepping than treadmills: A longitudinal study of pre-walking infants with Down syndrome

Abstract Importance Children with Down syndrome (DS), a genetic condition associated with neuromotor impairments, walk ∼1 year later than typically developing peers. Treadmill training is the most successful known intervention for accelerating walking onset in DS. Overground stepping with mobility devices better mimics critical properties of real-world walking, but it is unknown how overground stepping develops in pre-walking infants with DS. Objective We aimed to characterize the developmental trajectory of stepping quantity and quality in supported overground stepping compared to supported treadmill stepping. We also measured infants’ ability to self-propel in the walker. Finally, we assessed caregivers’ perspectives on both devices. Design We tested infants at 10, 13, 16, and/or 19 months of age. Setting This study occurred in a university laboratory in the United States. Participants We tested 31 pre-walking infants with Down syndrome across 69 sessions. Exposure At each session, infants completed four trials per task (treadmill and walker) and a test of self-propulsion in the walker. Main Outcomes and Measures We measured step quantity (overall step rate and alternating step rate), step quality (percentage of steps that were alternating, forward, and flat-landing), the ability to self-propel the walker, and caregiver perspectives on both devices. Results Step quantity increased with age and varied by task—infants took more steps per minute in the walker compared to the treadmill. Moreover, steps were of equal or higher quality in the walker. By 16 months, about half of infants could self-propel. Caregivers viewed both devices favorably, though the majority preferred the walker for home and/or community use. Conclusions Overground walkers promote more stepping than a treadmill in pre-walking infants with DS, with stepping of similar or higher quality. Caregivers feel positively about overground walkers. Relevance Overground stepping using a suspension walker shows promise as an intervention for pre-walking infants with Down syndrome.